The overall objective of the proposed research is to determine the relationship of brain biogenic amines and pituitary secretion of luteinizing hormone (LH) and prolactin. The unique feature of this study is the methodology for the in vivo determination of biogenic amines in various areas of the brain. By using electrochemical methods involving a carbon tipped electrode, dopamine (DA) or norepinephrine (NE) or serotonin (5-HT) can be measured at various sites in the brain simultaneously while blood samples are being taken for prolactin, LH and progesterone assay. This will be done in unanesthetized, unrestrained rats during different physiological conditions. The conditions to be investigated invlove widely divergent plasma levels of LH and prolactin, such as occurs during pregnancy, pseudopregnancy and lactation, times of elevated prolactin and depressed LH secretion. Other conditions such as ovariectomy result in an opposite hormonal pattern, with LH increased and prolactin levels suppressed. Finally, one condition in which both hormones are elevated, during proestrus, will also be studied for biogenic amine changes. The primary brain areas to be studied include the arcuate-median eminence area, The preoptic area and the caudate nucleus. With this study a better understanding of what change in biogenic amine release occurs in the central nervous system during normal physiological changes in prolactin and LH.